The present invention relates to an apparatus and method for reversing an output shaft rotation, and in particular a reverse gear shifter and a method for reversing output shaft rotation of a powered tool during the insertion of a pedicle screw.
Power tools used in inserting and retracting fasteners are well known. For instance, drills or powered screw drivers are widely utilized in inserting and removing screws from substrates in carpentry and the like. These devices typically have a shaft that is designed to rotate in two directions (i.e., one for insertion and one for removal). The mechanisms for causing the different rotation vary. In some instances, multiple triggers are provided for causing the different directional rotation. In other cases, an actuator is provided that causes a single trigger to provide the different rotation.
Power tools are also widely utilized in orthopedic surgery, especially in connection with the insertion and removal of bone screws. For instance, pedicle screws are widely utilized in spinal fusion procedures. These screws typically include a bone screw portion and a tulip that is polyaxially associated therewith. During insertion, a driver tool is coupled to both of those components and the bone screw portion is driven into the pedicle of a vertebral body. Thereafter, the tool must be removed by imparting an opposite force upon the portion of the tool engaging the tulip while not imparting a similar force on the bone screw portion. This is typically achieved by disengaging the tool from the bone screw portion and operating the driver in a manner that allows for the opposition rotation on the portion engaging the tulip.
The tools utilized in pedicle screw insertion are often somewhat cumbersome to utilize and not intuitive for a surgeon. For instance, drivers may require actuation of one button for insertion of the pedicle screw and another button for disengagement of the tool therefrom. Given the advent of more user friendly tools for performing surgical procedures, such as the use of robots, there is a need for easy and intuitive tools for performing such procedures, for instance, in the insertion of pedicle screws.